System for generating power from a syngas fermentation process

ABSTRACT

A system and process is provided for generating power from a syngas fermentation process. The process includes contacting hot syngas having a temperature above about 1400° F. with cooled syngas to produce a pre-cooled syngas having a temperature of 1400° F. or less at an inlet of a waste heat boiler. A waste heat boiler receives the pre-cooled syngas and is effective for producing waste heat boiler high pressure steam and a cooled syngas.

This application claims the benefit of U.S. Provisional Application Nos.61/516,667, 61/516,704 and 61/516,646, all of which were filed on Apr.6, 2011, and all of which are incorporated in their entirety herein byreference.

BACKGROUND

A system and process is provided for generating power from a syngasfermentation process. More specifically, a process is provided forgenerating high pressure steam from gasification and fermentation ofsyngas.

Microorganisms can produce ethanol and other compounds from carbonmonoxide (CO) through fermentation of gaseous substrates. The CO isoften provided to the fermentation as part of a gaseous substrate in theform of a syngas. Gasification of carbonaceous materials to produceproducer gas or synthesis gas or syngas that includes carbon monoxideand hydrogen is well known in the art. Typically, such a gasificationprocess involves a partial oxidation or starved-air oxidation ofcarbonaceous material in which a sub-stoichiometric amount of oxygen issupplied to the gasification process to promote production of carbonmonoxide.

Syngas produced by gasification processes described in the art can behot and needs cooling prior to downstream processing and subsequentfermentation. Hot syngas comprising carbon monoxide generated in agasification apparatus, is cooled in a heat exchanger or waste heatboiler downstream of the gasification apparatus, see for example U.S.Pat. No. 6,435,139; U.S. Pat. No. 7,587,995 and U.S. Pat. No. 7,552,701.Recovery and use of this heat content of hot syngas can be veryimportant for process economics.

SUMMARY

A process and system are provided that effectively generate highpressure steam from a syngas fermentation process. The process includescontacting hot syngas having a temperature above about 1400° F. withcooled syngas to produce a pre-cooled syngas having a temperature of1400° F. or less at an inlet of a waste heat boiler. A waste heat boilerreceives the pre-cooled syngas and is effective for producing waste heatboiler high pressure steam and a cooled syngas.

A system is provided for generating high pressure steam from a syngasfermentation process. The system includes a waste heat boiler positionedto receive syngas having a temperature of 1400° F. or less. The wasteheat boiler effective for producing waste heat boiler high pressuresteam and cooled syngas. A vent gas burner receives lean syngas from afermentor and the vent gas burner is effective for producing hot ventgas burner gas. A vent gas boiler superheater receives the hot vent gasburner gas and the vent gas boiler superheater is effective forproducing vent gas boiler high pressure steam. A steam mixer receivesand mixes the waste heat boiler high pressure steam and the vent gasboiler high pressure steam to produce a combined high pressure steam.

In another aspect, a process is provided for generating high pressuresteam from a syngas fermentation process. The process includescombusting carbonaceous materials in a gasifier to form a hot syngashaving a temperature above about 1400° F. and pre-cooling the syngas toproduce a pre-cooled syngas having an average temperature of 1400° F. orless at an inlet of a waste heat boiler. A waste heat boiler receivesthe pre-cooled syngas and is effective for producing waste heat boilerhigh pressure steam and a cooled syngas. A fermentor receives cooledsyngas. A vent gas burner receives lean syngas from an outlet of thefermentor and the vent gas burner is effective for producing hot ventgas boiler gas. A vent gas boiler superheater receives the hot vent gasburner gas and waste heat boiler high pressure steam and produces acombined high pressure steam.

BRIEF DESCRIPTION OF FIGURES

The above and other aspects, features and advantages of several aspectsof the process will be more apparent from the following drawings.

FIG. 1 is a general overview of a system that includes a waste heatboiler and vent gas boiler.

FIG. 2A and FIG. 2B illustrate an alternative aspect of a waste heatboiler system.

FIG. 3 illustrates an alternative aspect of a vent gas boiler system.

FIG. 4 is a general overview of another aspect of a system that includesa waste heat boiler and vent gas boiler.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousaspects of the present process and apparatus. Also, common butwell-understood elements that are useful or necessary in commerciallyfeasible aspects are often not depicted in order to facilitate a lessobstructed view of these various aspects.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense, but ismade merely for the purpose of describing the general principles ofexemplary embodiments. The scope of the invention should be determinedwith reference to the claims.

The process and system described herein effectively convert heatgenerated during gasification and fermentation of syngas into highpressure steam for generation of electrical power. The methods andsystem provide an excess of electrical power over what is needed for theoverall system.

DEFINITIONS

Unless otherwise defined, the following terms as used throughout thisspecification for the present disclosure are defined as follows and caninclude either the singular or plural forms of definitions belowdefined:

The term “about” modifying any amount refers to the variation in thatamount encountered in real world conditions, e.g., in the lab, pilotplant, or production facility. For example, an amount of an ingredientor measurement employed in a mixture or quantity when modified by“about” includes the variation and degree of care typically employed inmeasuring in an experimental condition in production plant or lab. Forexample, the amount of a component of a product when modified by “about”includes the variation between batches in a multiple experiments in theplant or lab and the variation inherent in the analytical method.Whether or not modified by “about,” the amounts include equivalents tothose amounts. Any quantity stated herein and modified by “about” canalso be employed in the present disclosure as the amount not modified by“about”.

“Carbonaceous material” as used herein refers to carbon rich materialsuch as coal, and petrochemicals. However, in this specification,carbonaceous material includes any carbon material whether in solid,liquid, gas, or plasma state. Among the numerous items that can beconsidered carbonaceous material, the present disclosure contemplates:carbonaceous material, carbonaceous liquid product, carbonaceousindustrial liquid recycle, carbonaceous municipal solid waste (MSW ormsw), carbonaceous urban waste, carbonaceous agricultural material,carbonaceous forestry material, carbonaceous wood waste, carbonaceousconstruction material, carbonaceous vegetative material, carbonaceousindustrial waste, carbonaceous fermentation waste, carbonaceouspetrochemical co products, carbonaceous alcohol production co-products,carbonaceous coal, tires, plastics, waste plastic, coke oven tar,fibersoft, lignin, black liquor, polymers, waste polymers, polyethyleneterephthalate (PETA), polystyrene (PS), sewage sludge, animal waste,crop residues, energy crops, forest processing residues, wood processingresidues, livestock wastes, poultry wastes, food processing residues,fermentative process wastes, ethanol co-products, spent grain, spentmicroorganisms, or their combinations.

The term “fibersoft” or “Fibersoft” or “fibrosoft” or “fibrousoft” meansa type of carbonaceous material that is produced as a result ofsoftening and concentration of various substances; in an examplecarbonaceous material is produced via steam autoclaving of varioussubstances. In another example, the fibersoft can include steamautoclaving of municipal, industrial, commercial, and medical wasteresulting in a fibrous mushy material.

The term “municipal solid waste” or “MSW” or “msw” means waste that mayinclude household, commercial, industrial and/or residual waste.

The term “syngas” or “synthesis gas” means synthesis gas which is thename given to a gas mixture that contains varying amounts of carbonmonoxide and hydrogen. Examples of production methods include steamreforming of natural gas or hydrocarbons to produce hydrogen, thegasification of coal and in some types of waste-to-energy gasificationfacilities. The name comes from their use as intermediates in creatingsynthetic natural gas (SNG) and for producing ammonia or methanol.Syngas is combustible and is often used as a fuel source or as anintermediate for the production of other chemicals.

In one aspect, gasification of carbonaceous materials provides syngas.Gasification involves partial combustion of biomass in a restrictedsupply of oxygen. The resultant gas includes CO and H₂. In this aspect,syngas will contain at least about 20 mole % CO, in one aspect, about 20to about 100 mole % CO, in another aspect, about 30 to about 90 mole %CO, in another aspect, about 40 to about 80 mole % CO, and in anotheraspect, about 50 to about 70 mole % CO. The syngas will have a CO/CO₂ratio of at least about 0.75. Ser. Nos. 61/516,667, 61/516,704 and61/516,646 describe some examples of suitable gasification methods andapparatus (U.S. Ser. Nos. 61/516,667, 61/516,704 and 61/516,646, all ofwhich were filed on Apr. 6, 2011, and all of which are incorporatedherein by reference). Syngas leaving the gasifier will have atemperature above about 1400° F., and in another aspect, at least about1400° F. to about 3500° F. The gasification process is effective fordestruction of tars.

The terms “fermentation”, fermentation process” or “fermentationreaction” and the like are intended to encompass both the growth phaseand product biosynthesis phase of the process. In one aspect,fermentation refers to conversion of CO to alcohol.

High Pressure Steam System

FIG. 1 illustrates a system for generating high pressure steam. As shownin FIG. 1, the process and system provide a blended sygnas 120 byblending hot syngas 110 leaving a gasifier (not shown) with recycledcooled syngas. Recycled cooled syngas 140 contacts hot syngas 110 afterleaving the gasifier. The recycled cooled syngas 140 contacts the hotsyngas 110 at a point after the hot syngas leaves the gasifier andbefore the blended syngas 120 enters the waste heat boiler 100. In thisaspect, the recycled cooled syngas 140 has a temperature of about 350°F. to about 450° F. A conduit or pipe transfers the recycled cooledsyngas 140 to the hot syngas 110. Transfer of the recycled cooled sygnas140 provides a ratio of recycled cooled syngas 140 to hot syngas ofabout 0.1 to about 20. In other aspect, ratios of recycled cooled syngasto hot syngas may include about 1 to about 15, about 1 to about 10,about 1 to about 5, about 1 to about 4, about 1 to about 3, about 1 toabout 2, and about 1 to about 1.

The blended syngas 120 has an average temperature of about 1400° F. orless, in another aspect, about 600° F. to about 1400° F., in anotheraspect, about 750° F. to about 1400° F., in another aspect, about 600°F. to about 1400° F., in another aspect, about 750° F. to about 1200°F., in another aspect, about 750° F. to about 900° F., in anotheraspect, about 750° F. to about 825° F., and in another aspect, about600° F. to about 900° F. The blended syngas 120 reaches thesetemperatures prior to entering the waste heat boiler 100. In thisaspect, a thermocouple measures temperature at an inlet to the wasteheat boiler prior to entering the waste heat boiler 100. Thethermocouple may be positioned at any position across a diameter of theinlet.

As used herein, “average temperature” can be determined using knownmethods utilized to determine multiple temperatures across a diameterand then express those multiple temperature measurements as an average.In one aspect, computer modeling (including CFD) may be used to providean average temperature. In other aspects, multiple temperaturemeasurements may be made using temperature sensors such asthermocouples, infrared, radar, and the like.

As further shown in FIG. 1, the process and system provides blendedsyngas 120 to a waste heat boiler 100. The waste heat boiler 100 may beany know type of waste heat boiler effective for providing heat transferfrom the blended syngas 120. In this aspect, the waste heat boiler 100receives water/steam 160 and the waste heat boiler is effective forproviding cooled sygnas 130 and waste heat boiler high pressure steam170. In this aspect, the waste heat boiler high pressure steam 170 has apressure of about 50 psig to about 950 psig. The process and systemincludes recycling 140 a portion of the cooled syngas 130 from the wasteheat boiler 100 to the hot syngas 110. A fermentor receives cooledsyngas 130 that is not recycled 150.

A vent gas burner 200 receives lean syngas 210 or off gas from afermentor. The lean syngas 210 will typically have a CO/CO₂ ratio ofless than about 1.0, in another aspect, about 0.01 to about 1.0, inanother aspect, about 0.01 to about 0.5, and in another aspect, about0.01 to about 0.1. The lean syngas may have higher concentrations of COin the event of lower CO conversions in the fermentor. In this aspect,the lean syngas 210 or off gas may have a CO/CO₂ ratio of more thanabout 0.1. The vent gas burner 200 burns the lean syngas 210. Transferof air 220 to the vent gas burner 200 may enhance combustion. Vent gasburners 200 may include any of those known in the art. The vent gasburner 200 provides a hot vent gas burner gas 230. In this aspect, thevent gas burner gas has a temperature of about 1500° F. to about 3000°F.

A vent gas boiler superheater 300 receives hot vent gas burner gas 230.Vent gas boiler superheaters may include any of those known in the art.The vent gas boiler superheater 300 receives water/steam 310 and thevent gas boiler superheater 300 provides a cooled vent gas boiler gas320 and vent gas boiler high pressure steam 330. In this aspect, thevent gas boiler high pressure steam 330 has a pressure of about 600 psigto about 950 psig, and in another aspect, about 875 psig to about 925psig. The vent gas boiler high pressure steam 330 and the waste heatboiler high pressure steam 170 are combined in a steam blender 180. Thesteam blender 180 provides a combined high pressure steam 400 having apressure of about 600 psig to about 950 psig, and in another aspect,about 875 psig to about 925 psig. The combined high pressure steam 400is utilized for production of power. Examples of equipment which may beutilized to produce power from high pressure steam include those knownin the art, for example, steam turbines. In this aspect, increasingsteam pressure from about 600 psig to about 900 psig will result in anet power gain.

In another aspect, the system may include steam drums (not shown)between the waste heat boiler 100 and steam blender 180, and between thevent gas boiler superheater 300 and steam blender 180.

An alternative configuration of a waste heat boiler is shown in FIG. 2A.This aspect includes both a waste heat boiler 100 and a waste heatboiler preheater 101 (also referred to as an economizer). As shown inFIG. 2A, the process and system provide a blended syngas 120 by blendinghot syngas 110 leaving a gasifier (not shown) with recycled cooledsyngas 140. As described herein, gasification of carbonaceous materialsmay provide sygnas. Syngas will contain at least about 20 mole % CO, andwill have a temperature above about 1400° F. The waste heat boiler 100provides a semicooled syngas 125. In this aspect, the semicooled syngas125 has a temperature of about 500° F. to about 750° F.

A waste heat boiler preheater 101 receives the semicooled syngas 125.The waste heat boiler preheater 101 receives water/steam 160 andprovides cooled syngas 130 and preheated water/steam 165. The processand system includes recycling 140 a portion of the cooled syngas 130from the waste heat boiler preheater 101 to the hot syngas 110. Afermentor receives cooled syngas 130 that is not recycled 150. The wasteheat boiler 100 receives the preheated water/steam 165 from the wasteheat boiler preheater 101. The waste heat boiler 100 is effective forproviding cooled sygnas 130 and waste heat boiler high pressure steam170.

In another aspect as shown in FIG. 2B, the process and system includesrecycling a portion of the semicooled syngas 125 from the waste heatboiler 100 to the hot syngas 110. The waste heat boiler preheater 101receives a portion of the semicooled sygnas that is not recycled 126. Inanother aspect, the configuration is shown in FIGS. 2A and 2B mayinclude steam drums (not shown). A steam drum may be positioned toreceive preheated water/steam 165.

FIG. 3 illustrates an alternative configuration of a vent gas boilersuperheater system. In this aspect, a vent gas boiler superheater 300receives hot vent gas burner gas 230. The vent gas boiler superheater300 receives preheated steam 312 and provides vent gas boiler highpressure steam 330 and semicooled vent gas boiler gas 322. In thisaspect, vent gas boiler high pressure steam 330 has a pressure of about600 psig to about 950 psig, and the semicooled vent gas boiler gas 322has a temperature of from about 2000° F. to about 2500° F. In oneaspect, a vent gas boiler steam generator 301 receives the semicooledvent gas boiler gas 322. The vent gas boiler steam generator 301receives preheated water/steam 311 and provides preheated steam 312 andsemicooled vent gas boiler gas 321. In another aspect, a vent gas boilerfeed water preheater 302 receives the semicooled vent gas boiler gas321. The vent gas boiler feed water preheater 302 receives water/steam310 and provides preheated water/steam 311 and cooled vent gas boilergas 320. In another aspect, the configuration shown in FIG. 3 mayinclude a steam drum (not shown) positioned to receive preheated steam331 and may provide water/steam 310.

FIG. 4 illustrates another aspect of a system for generating highpressure steam. As shown in FIG. 4, a vent gas boiler superheater 300receives hot vent gas burner gas 230. The vent gas boiler superheater300 receives preheated steam 312 and provides vent gas boiler highpressure steam 330 and semicooled vent gas boiler gas 322. In thisaspect, the preheated steam 312 is provided by blending waste heatboiler high pressure steam 170 with preheated steam 331 from the ventgas boiler steam generator. The resulting vent gas boiler high pressuresteam 330 has a pressure of about 600 psig to about 950 psig. Theconfiguration shown in FIG. 4 may also include a steam drum (not shown)positioned to receive preheated steam 331.

In one aspect, the vent gas burner gas has a temperature of about 1500°F. to about 3000° F. The vent gas boiler superheater 300 also receiveswaste heat boiler high pressure steam 170. The vent gas boilersuperheater 300 receives water/steam 310 and the vent gas boilersuperheater 300 provides a cooled vent gas boiler gas 320 and a combinedhigh pressure steam 400 having a pressure of about 600 psig to about 950psig. The combined high pressure steam 400 is utilized for production ofpower. In this aspect, mixing waste heat boiler steam with vent gasboiler steam prior to superheating instead of mixing the waste heatboiler steam after the vent boiler steam is already superheated willresult in a net power gain.

EXAMPLES Example 1 Effect of Syngas Cooler Inlet Temperature on HeatTransfer and Fouling

A gasifier having the design described herein was operated with thetemperatures and flow rates described below. A fouling factor wasdetermined as indicated.

Fouling factor at 600° F. inlet temperature to the syngas cooler:

Temperature Syngas Fouling of Syngas at Feed Rate Factor AccumulatedInlet of Syn- to Cooler Btu/ Time (hrs) gas Cooler (° F.) (lb/hr) (ft²h° F.) 7.7 601 477 0.022 15.7 614 512 0.034 23.7 597 862 0.009 31.7 608730 0.008 40 605 1647 0.002 56 597 432 0.023 64.7 593 705 0.011 72 577618 0.014 80 595 596 0.019 89 577 1416 0.007 188.15 583 355 0.006 196572 372 0.024 207.7 565 345 0.048 216 577 317 0.034 223.7 572 385 0.024

Average fouling factor at 600° F. inlet was 0.019 Btu/(ft²h° F.).

A gasifier having the design described herein was operated with lowersyngas cooler inlet temperatures and flow rates described below. Afouling factor was determined as indicated.

Fouling factor at 1300° F. inlet temperature to the syngas cooler:

Temperature Syngas Fouling of Syngas at Feed Rate Factor AccumulatedInlet of Syn- to Cooler Btu/ Time (hrs) gas Cooler (° F.) (lb/hr) (ft²h° F.) 7.5 1297 288 0.042 19.5 1293 314 0.070 105.5 1295 215 0.119 118.51295 230 0.100 129.5 1294 194 0.123 153.5 1297 191 0.098 166.5 1295 1980.096 177.5 1295 233 0.072 190.5 1297 209 0.099 260.5 1308 240 0.050273.5 1302 214 0.067 285.5 1301 183 0.082 298.5 1295 229 0.078 309.51296 264 0.080 317 1314 240 0.097 326.5 1328 275 0.078 338.83 1322 2910.068 346.5 1332 281 0.070 350.5 1346 312 0.071 368.5 1336 213 0.081374.5 1335 263 0.074

Average fouling factor at 1300° F. inlet was 0.078 Btu/(ft²h° F.).

While the invention herein disclosed has been described by means ofspecific embodiments, examples and applications thereof, numerousmodifications and variations could be made thereto by those skilled inthe art without departing from the scope of the invention set forth inthe claims.

1. A process for generating high pressure steam from a syngasfermentation process, the process comprising: contacting hot syngashaving a temperature above about 1400° F. with cooled syngas to producea pre-cooled syngas having a temperature of 1400° F. or less at an inletof a waste heat boiler; and transferring the pre-cooled syngas to thewaste heat boiler effective for producing waste heat boiler highpressure steam and a cooled syngas.
 2. The process of claim 1 furthercomprising transferring lean syngas to a vent gas burner effective forproducing hot vent gas burner gas; transferring the hot vent gas burnergas to a vent gas boiler superheater effective for producing vent gasboiler high pressure steam; and combining the waste heat boiler highpressure steam and vent gas boiler high pressure steam to form acombined high pressure steam.
 3. The process of claim 1 wherein hotsygnas is cooled by blending with cooled recycled syngas having atemperature of about 350° F. to about 450° F.
 4. The process of claim 3wherein the recycled cooled syngas is blended with the hot syngas at aratio of about 0.1 to about
 20. 5. The process of claim 1 wherein thepre-cooled syngas has a temperature of about 600° F. to about 1400° F.6. The process of claim 5 wherein the pre-cooled syngas has atemperature of about 600° F. to about 900° F.
 7. The process of claim 1wherein the waste heat boiler high pressure steam has a pressure ofabout 50 psig to about 950 psig.
 8. The process of claim 2 wherein thevent gas burner gas has a temperature of about 1500° F. to about 3000°F.
 9. The process of claim 2 wherein the vent gas boiler high pressuresteam has a pressure of about 600 psig to about 950 psig.
 10. Theprocess of claim 2 wherein the combined high pressure steam has apressure of about 600 psig to about 950 psig.
 11. The process of claim 1wherein preheated water and/or steam is supplied to the waste heatboiler from a waste heat boiler preheater.
 12. The process of claim 2wherein the combined high pressure steam is utilized for production ofpower.
 13. A system for generating high pressure steam from a syngasfermentation process, the system comprising: a waste heat boilerpositioned to receive syngas having a temperature of 1400° F. or less,the waste heat boiler effective for producing waste heat boiler highpressure steam and cooled syngas; a vent gas burner positioned toreceive lean syngas from a fermentor, the vent gas burner effective forproducing hot vent gas burner gas; a vent gas boiler superheaterpositioned to receive the hot vent gas burner gas, the vent gas boilersuperheater effective for producing vent gas boiler high pressure steam;and a steam mixer positioned to receive and mix the waste heat boilerhigh pressure steam and the vent gas boiler high pressure steam toproduce a combined high pressure steam.
 14. The system of claim 13wherein the blended syngas has a temperature of about 600° F. to about1400° F. at an inlet of the waste heat boiler.
 15. The system of claim14 wherein the blended syngas has a temperature of about 600° F. toabout 900° F.
 16. The system of claim 13 wherein the waste heat boilerhigh pressure steam has a pressure of about 50 psig to about 950 psig.17. The system of claim 13 wherein the vent gas boiler gas has atemperature of about 1500° F. to about 3000° F.
 18. The system of claim13 wherein the vent gas boiler high pressure steam has a pressure ofabout 600 psig to about 950 psig.
 19. The system of claim 13 wherein thecombined high pressure steam has a pressure of about 600 psig to about950 psig.
 20. The system of claim 13 wherein the combined high pressuresteam is utilized for production of power.
 21. A process for generatinghigh pressure steam from a syngas fermentation process, the processcomprising: combusting carbonaceous materials in a gasifier to form ahot syngas having a temperature above about 1400° F.; pre-cooling thesyngas to produce a pre-cooled syngas having an average temperature of1400° F. or less at an inlet of a waste heat boiler; transferring thepre-cooled syngas to the waste heat boiler effective for producing wasteheat boiler high pressure steam and a cooled syngas; introducing cooledsyngas into a fermentor: transferring lean syngas from an outlet of thefermentor to a vent gas burner effective for producing hot vent gasboiler gas; and transferring the hot vent gas burner gas and waste heatboiler high pressure steam to a vent gas boiler superheater effectivefor producing a combined high pressure steam.
 22. The process of claim21 wherein sygnas is cooled by blending with cooled recycled syngashaving a temperature of about 350° F. to about 450° F.
 23. The processof claim 22 wherein the recycled cooled syngas is blended with the hotsyngas at a ratio of about 0.1 to about
 20. 24. The process of claim 21wherein the pre-cooled syngas has a temperature of about 600° F. toabout 1400° F. at an inlet of the waste heat boiler.
 25. The process ofclaim 24 wherein the pre-cooled syngas has a temperature of about 600°F. to about 900° F. at an inlet of the waste heat boiler.
 26. Theprocess of claim 21 wherein the waste heat boiler high pressure steamhas a pressure of about 50 psig to about 950 psig.
 27. The process ofclaim 21 wherein the vent gas burner gas has a temperature of about1500° F. to about 3000° F.
 28. The process of claim 21 wherein thecombined high pressure steam has a pressure of about 600 psig to about950 psig.
 29. The process of claim 21 wherein preheated water and/orsteam is supplied to the waste heat boiler from a waste heat boilerpreheater.
 30. The process of claim 21 wherein the combined highpressure steam is utilized for production of power.